| 摘要 |
PROBLEM TO BE SOLVED: To quickly detect an obstacle that suddenly appears. SOLUTION: A CCD camera picks up the image ahead of a vehicle, and imaged video is subjected to differential processing to prepare an image obtained by enhancing horizontal and vertical contours. The image is subjected to discrete cosine transformation, to calculate an information distribution in a frequency space. Information change in the image is detected from the arrangement of DCT coefficients showing the information distribution in the frequency space. That is, when a vehicle and a person appear suddenly in the image, the value of the DCT coefficient at a prescribed position increases in response to the vehicle and the person. Then, when the value of the DCT coefficient at the prescribed position increases equally to or more than a set value, it is possible to detect that a vehicle and a person corresponding to the position appear. For instance, when the 16-th, 26-th and 29-th coefficients in which only a horizontal frequency is high are increased, it can be detected that a vehicle appeared in an image pickup space. |
